Fluid pressure producing device



April 17, 1945. R. R. GUNDERSON FLUiD PRESSURE PRODUCING DEVICE FiledSept. 28, 1942 hm Qv mm mm IN V EN TOR.

N o s R E D N U G R H P L A R AITORNEYS Patented Apr. 17, 1945 FLUIDPRESSURE recurrence i.

Ralph -R.Gunderson, Detroit, Mich. l Application September 28, no,summoned;

Q GClaims. i j

The invention relates to fluid pressure producy ing devices and refersmore particularly to devices of that type fordischarginga large volumeoffluid under. low pressure during the first stage and then discharging asmall volume of fluid under,high,-;-1

pressure during the second stage.

.The. invention has for one of its objects to provide. an improved fluidpressure producing device having a low pressure producing device and ahigh pressure producing device and so cozi-:; ;=l0.

:structed that the devices operate separately and :successively.

'The invention has for another object to pro .vide a fluid pressureproducing device in which the low pressure and high pressureproducing-$215 devices are adapted to communicate with acommon outletthrough separate independent-passages. l 11 The invention has foraiurther object to provides, fluid pressure producing devicehavinglawn-.2

pressure and high pressure producing. devices "opposed: and formed of acylinder member having low pressure and high pressure cylinders, lowpressuteand high pressure pistons slidable within the separate passagesbetween the cylinders and the common outlet and operable to trap thefluid either in one or the-other of the cylinders to thereby hold thecylinder member from endwise,

of the pistons I v The invention has for other objects to provide animproved construction of valve mechanism for -contro1ling the passagesand to provide the valve mechanism with a valvewhich is operable only'during the return of the parts to their oil posi- "tion' to permit theflow of fluid from the low pressure cylinder to the high pressurecylinder.

f -With these as well as other objects in 40 the invention resides inthe novel features ofc'onstruction and combinations and arrangements orparts, as more fully hereinafter'set forth. In the drawing:

. Figure I is a vertical central section through $5 a fluid pressureproducing device embodying the invention; v

'. Figure 21s a cross section. on the linel -z oiFIeure I; y p ."liigure3 is an enlarged. view of a. portion' ofjfl j lligure 1 showing theparts in 'difl'erent posil The fluid pressure producing deviceembodyling 'the invention is designed. particularly for usellilfal'piPlyine the brakes-eta motor vehicle through .w sel iiaedes conecte to the outlet or the devicm although it is apparent that;v thedevice may be otnerwisezuseoesi for p e. in pp .ing;a;brake of anairplane landing wheel through arwh c mind r. I a -As shownwin thedrawing. the fluid pressure producing-device comprises the cylindermember l'naving intermediate its ends an outlet formed of the outletchamber Z and the outlet port 3,

whicnlatteris adapted to be. connectedto, the fluid-line leading toeither, one or more wheel cylindersior operatingone': or more brakes.The

cylinder member has at oppositesidcs of the out- .lettthe, axiallyaligned. low pressure cylinder. 3 and high pressure. cylindert, theformer having landinternalodiameter larger than the internal diameter orthe latter. The cylinder member, also has separatepassages 6 and.Ebetwe'en the low pressurercsrlinder-andoutlt and thehighpressurecylinder andoutletu The passage Sis provlded hymbores;extendingthrough the plug 1 .whichI-is threaded into the; portion of theintermediate partition wallil'. of the cylinder member betweentheinncrcnd of the low pressure cylinder the cylinders, and valvemechanismeontrolling and the outlet chamber. The passage 8 is formed bya boreflwhich 'extendsthrough the portion of the mtermediate: partitionwall I" between the v innerend oi the high pressure cylinder and theoutlet chamber. movement-with respect to the one or the other 5 thepressure piston withfn h pressure cylinder and H} is th high pressurepiston within the high pressure eylindenthetwopistons being relativelymovable 'towardeach other'and the outletduring their for relativelyretracting the pistons and cylinder member and relatively moving thesame to off positions." The ofiposition of, the low pressure piston-lisdetermined by the abutment ling. l3 held inplace by the split ring {4'engaging an annular groove in the. open end of the low pressurecylinder, The on position of the high pres-- sure piston determined bythe'pin [5 extend- Qinfg throughandftl resdedv into the open endv of thehigh pressure'cylinder. Suitable sealing rings are provided. between thepistons and their cyltiers wan ing the escape of the braking fil which'a liquid, i is the fluid reservoir above preierably integral with thecylinder member This reservoir issuitably vented to the atmosphere andcommunicates with. the low presily apply the brake with portion of thepassage.

sure cylinder and the high pressure cylinder in the off positions oftheir respective pistons through the openings 11 and I8, respectively,which are located in the portions of the cylinder walls immediatelybelow the reservoir.

The pistons carry the cylinder member and reservoir and one of thepistons is pivotally connected to a pedal and the other pivotallyconnected to a support. In the event that the fluid pressure producingdevice is used in applying the brakes of a motor vehicle, one of thepistons is pivotally connected beyond the cylinder member to the footpedal of the motor vehicle, while the other of the pistons is pivotallyconnected beyond the cylinder member to a support upon the chassis ofthe motor vehicle. I

19 is a valve mechanism constructedto compel the low pressure producingdevice which is formed of the low pressure cylinder and piston and thehigh pressure producing device which is formed of the high pressurecylinder and piston to operate separately and in sequence when actuated.

The valve mechanism normally occupies a position opening the passage 6between the low pressure cylinder and the outlet and closing the passage8 between the high pressure cylinder and the outlet. As a result, whenthe pedal is depressed to actuate the fluid pressure producing device,fluid is trapped in the high pressure cylinder during the first stageand the high pressure piston acts on the fluid trapped in the highpressure cylinder to-hold the cylinder member from endwise movementrelative to the high pressure piston and to compel the low pressurecylinder to advance relative to the low pressure piston to force thefluid directly to the outlet and then to one or more wheel cylinders forapplying one or more brakes. When the pressure developed within the highpressure cylinder becomes sufllcient, the valve mechanism is moved topositions successively closing the passage 6 and opening the passage 8so that upon continued actuation of the fluid. pressure producing devicefluid is trapped in the low pressure cylinder and the low pressurepiston acts on the fluid trapped in the low pressure cylinder to holdthe cylinder membar from endwise movement relative to the low pressurepiston and to compel the high pressure piston to advance within the highpressure cylinder to force the liquid directly to the outlet and then tothe one or more wheel cylinders for applying the one or more brakesunder a higher pressure than that during the first stage. It will benoted that the pressure of the fluid trapped in the high pressurecylinder is much greater than that of the fluid being forced from thelow pressure cylinder because of the difierence in internal diameters ofthe two cylinders. Pressure of the fluid discharged from the lowpressure cylinder during the first stage is preferably that required totake up brake clearance, while the pressure of fluid discharged from thehigh pressure cylinder during the second stage is suflicient to veryreadthe desired force.

The valve mechanism l9 comprises the valve 20 having a head slidablewithin anenlarged portion of the passage 8 and a stem slidable withinthe bore 2| extending axially of the plug 1. The head is preferablyprovided with a suitable sealing ring engageable with the wall of theenlarged The valve 20 is normally held in a position closing the passage8 by the coil spring. 22 between the bottom 23 of the plug 1 and the endof the valve stem, this spring normally holding the head against theshoulder 24 formed by the reduced portion of the passage 8. The valvemechanism also comprises the secand valve 25 which is in the nature of arubber disc sleeved upon the stem of the valve 20 and adapted to bemoved to a position to close the passage 6. 25 is a suitable collar alsosleeved on the stem of the valve 20 and engageable in the recess 21formed in the plug 1 at the ends of the bores forming the passage 6 toprevent the valve from being forced into the bores. The collar 25 isengageable with the annular shoulder 28 formed on the stem of th valve20 to limit the movement of the valv 25 toward the passage 6. The collaris normally held in engagement with the shoulder by the coil spring 29encircling the stem of the valve 20 and abutting the valve 25 and thehead of the valve 20, the spring permitting movement of the valve 26relative to the valve 20 after the valve 25 has closed the passage 6 andduring continued movement of the valve 20 to open position.

With the construction as thus far described, it will be seen that withthe parts in their oil positions, as shown in Figure 1, upon actuationof the fluid pressur producing device the low pressure piston 9 and thehigh pressure piston 10 will be relatively moved toward each other untilthe high pressure piston close the port 18, at which time the fluidwithin the high pressure cylinder is trapped by the valve 2B. As aresult, the cylinder member l is held from endwise movement relative tothe high pressure piston 10 so that upon continued actuation thecylinder member I is advanced relative to the low pressure piston 9 toforce fluid through the passage 6, the outlet chamber 2 and the outletport 3 to the one or more wheel cylinders to apply the one or morebrakes. When all braking clearance is taken up. the pressure of thefluid built up within the high pressure cylinder is such that the fluidexerts a -move the same toward the outlet.

force upon the valve 20 which is greater than the strength of the spring22 so that the fluid in the high pressure cylinder acts upon the valve20 to During the first portion of the movement of this valve the valve25 closes th passage 6 between the low pressure cylinder and the outletso that fluid is trapped in the low pressure cylinder and the lowpressure piston acts to hold the cylinder member from endwise movementrelative to the low pressure piston and the high pressure piston isadvanced on its working stroke to move the valve 20 to a positionopening the passage 8 and to force the fluid to the outlet and then tothe one or more wheel cylinders to complete the application of the oneor more brakes. V

To relieve the low pressure cylinder during the relative retraction ofthe cylinder member and the low pressure piston to the on position ofthe low pressure piston, the low pressure piston is formed with theannular channel 30 which remains at all times in communication with theport 3| in the low pressure cylinder wall communicating with thereservoir. The low pressure piston is also formed with the transverseport 32 in itshead and carries the valve 33 located at the working orpressure side of its head and normally held in engagement with this sideby the coil spring 34. During the relative retraction of the cylindermember and the low pressure piston, this valve is moved to open positionso that fluid may flow from the reservoir through the port 3|, thechannel 30 and the port 32 into the portion of the low pressure cylinderin advance of the low pressure piston. To relieve the high pressurecylinder during the retraction of the high pressure piston, the valve 20is formed with the axial bore 35 extending therethrough and the bottomof the plug 1 is formed with the axial port 36. 31'is a valve carindermember relative to the low pressure piston, the pressure built up in thehigh pressure cylinder increases at a much greater rate than thepressure in the low pressure cylinder because of their diflerence indiameters so that the fluid in the high pressure cylinder serves toeasilyhold the valve 3! closed during the first stage of operation. Itwill be seen that during the retraction of the high pressure piston thevalve 35 is moved to open position to allow fluid to flow from the lowpressure cylinder into the high pressure cylinder. When the pistons arein their off positions, the compensating ports l1 and I8 are open andallow any excess fluid in the cylinders to return to the reservoir.

It will thus be seen that I have provided an improved construction offluid pressure producing device which acts in two successive stages,during the flrst of which a large volume of fluid under low pressure isdischarged and during the second of which a small volume of fluid underhigh pressure is discharged. It will also be seen that the structure issuch that the low pressure and high pressure producing devices operateseparately and successively and discharge fluid to a common outletthrough separate and independent passages. It will be further seen thatI have provided an improved construction of valve mechanism which isoperable to trap the fluid either in the low pressure producing deviceor in the high pressure producing device.

What I claim as my invention is:

. 1. A fluid pressure producing device comprisin a cylinder memberhaving cylinders of different diameters, an outlet and passages directlybetween said cylinders and outlet, pistons within said cylinders, andvalve mechanism controlling said passages, said valve mechanism beingmovable by the liquid under a pressure developed in the cylinder ofsmaller diameter and comprising a valve in the passage between thecylinder of smaller diameter and said outlet, and a second valve movableby said. first mentioned valve to close the passage between the cylinderof larger diameter and said outlet prior to opening of saidfirstmentioned valve, and means for normally maintaining said first mentionedvalve in closed position and said second valve in open position.

2. A fluid pressure producing device comprising a cylinder member havingcylinders of different diameters, an outlet and passages directlybetween said cylinders and outlet, pistons within said cylinders, andvalve mechanism controlling between the cylinder of larger diameter andsaid outlet and subsequently opening the passage be-'- tweenthe cylinderof smaller diameter and said outlet.

3. A fluid-pressure producing device comprising a cylinder member havingan outlet, a low pressure cylinder at one side of said outlet, a highpressure cylinder at the opposite side of said outlet, and separatepassages between said cylinders and outlet, pistons within saidcylinders and relatively movable toward each other during their pressurestroke, and valve mechanism controlling said passages, said valvemechanism being movable by'the fluid under a pressure developed in saidhigh pressure cylinder and serving to sucr cessively trap fluid in saidhigh pressure cylinder and low pressure cylinder and at the same timeoccupy positions successively opening the passages between said lowpressure cylinder and outlet and high pressure cylinder and outlet, saidvalve mechanism comprising a different valve from each passage with onevalve movable by ing a floating cylinder member having an outlet saidpassages, said valve mechanism normally occupying a position opening thepassage-between the cylinder of larger diameter and said outlet andclosing the passage between the cylinder of smaller diameter and saidoutlet, said valve mechanism being automatically movable by the fluidunder a pressure developed in the cylinder of smaller diameter to aposition closing the passage another valve and closingits" passage.prior'to the other valve opening its passage.

4. A fluid pressureproducing device comprising a cylinder member havingsubstantially axially aligned low pressure andhigh pressure cylinders,an outlet between said cylinders and independent passagesconnecting-said cylinders and outlet, pistons within said cylinders, andvalve mechanism controlling said passages, said valve mechanism beingmovable by the fluid under a pressure developed in said high pressurecylinder and comprising a valve in the passage connectin said highpressure cylinder and said outlet, a spring for resiliently holding saidvalve in a position closing the last mentioned passage, a second valvecarried by said first mentioned valve and spring between said valves forresiliently holding said second valve in a position to close itspassage.

5. A fluid pressure producing device comprisand cylinders of differentdiameters at opposite sides of and adapted to communicate with saidoutlet, opposed pistons within said cylinders and carrying said cylindermember, and means movable by the fluid under a pressure developed in oneof said cylinders for controllig the communication between saidcylinders and outlet operable to trap fluid in either ofsaid cylindersand to place either of said cylinders in communication with said outlet,said controlling means being operable to trap fluid in one of saidcylinders before .placing the other of said cylinders in communicationwith said outlet.

"6. A fluid pressure producing device compris ing a cylinder memberhaving an outlet, cylinders of different diameters at opposite sides-ofsaid outlet and separate passages between said cylin-- ders and outlet,pistons within said cylinders and opposed to each other, and'valvemechanism movable by fluid under apressure developed in one of saidcylinders and comprising a different valve for each :passagaone of saidvalves being movable by another valve and closing its passage prior tothe other valve opening its passage. RALPH R. GUNDERSON.

